1. Field of the Invention
The present invention relates to a liquid discharge head and a circuit board.
2. Description of the Related Art
A low voltage differential signal (LVDS) transmission scheme is one of differential transmission schemes as a data transfer scheme used in the field of precision equipment such as a liquid discharge apparatus. The LVDS transmission scheme is a scheme for transferring data using a pair of differential transmission lines, and is capable of transferring the data with much lower electric potential difference at a higher speed compared with a commonly used scheme for transferring data with a single line (hereinafter, referred to as a single-ended transmission scheme).
Japanese Patent Application Laid-Open No. 2005-199665 discusses a configuration for sending at high speeds using the LVDS transmission scheme, logical signals such as recorded data signals or clock signals for driving energy generating elements which generate energy for discharging a liquid. The signals are sent from the liquid discharge apparatus, via the differential transmission line within a circuit board (hereinafter, sometimes referred to as a flexible circuit board or a flexible board) made of a material provided in the liquid discharge head and having flexibility, to a liquid discharge head substrate including the energy generating elements.
However, a voltage required when the logical signals are transferred using the LVDS transmission scheme is smaller compared to a voltage utilized for energy generation from the energy generating elements. For this reason, even in the LVDS transmission scheme which is less susceptible to noises by taking differences of the signals between a pair of differential transmission lines, there is a possibility that a switching noise when voltage is applied to the energy generating elements may exert an influence upon transmission of the logical signals. For this reason, in a liquid discharge head discussed in Japanese Patent Application Laid-Open No. 2005-199665, there are concerns that transmission of the logical signals may not be normally performed under the influence of the switching noise, and operation may become unstable.
In the liquid discharge head that performs recording in a short time by discharging a liquid in unison from discharge ports of the liquid provided across a recording width of a recording medium, like the one used especially in the field of printing industry, a number of the energy generating elements to be simultaneously driven is increased. For this reason, it is conceivable that an electric current flowing through the flexible board also becomes large, and influence of the switching noise becomes noticeable. To reduce the influence of noises by keeping the differential transmission line used in the LVDS transmission scheme away from the line utilized for applying voltage for generation of energy, leads to an upsizing of the flexible board, and eventually to an upsizing of the apparatus, and therefore, that is not quite realistic.